Shortest Word Finder

Given a sentence, determine the shortest word according to the following rules:

• Ignore all punctuation marks.
• Words are compared in a case-insensitive manner.
• If multiple words share the same shortest length, return the first occurrence.
• If the input is empty or contains no valid word, output an empty string.

Note: To count the length of a word, use the standard formula:

$$ \text{Length}(w) = \sum_{i=1}^{n} 1 $$

inputFormat

The input consists of a single line containing a sentence.

outputFormat

Output the shortest word from the sentence.

## sample

The quick, brown fox jumps over the lazy dog.

the